The number of echoes combined into a single image or image set in multiple echo imaging sequences or echo-train techniques such as rapid acquisition with relaxation enhancement (RARE), fast-spin echo (FSE), and turbo spin-echo (TSE). In RARE imaging, the ETL typically equals the acceleration factor.
As for tooth pain, it is caused by a reaction of the nerves inside a tooth's pulp chamber with the severity dependent upon the type and degree of the stimulus. What follows are some examples of symptoms you may be feeling and their possible causes.
When a tooth hurts after root canal, Several factors may be involved . If temperature sensitivity or pain exists, its either another tooth next to the tooth in question, or an accessory or main nerve still exits in the tooth and the root canal needs to be retreated. If temperature does not cause any throbbing pain then a crack in the tooth, and a in ill fitting crown could cause it.